BAGHDAD, April 16 (UPI) -- Fighting erupted in two Shiite regions of Iraq, with four people dying Wednesday in a U.S. air strike in Basra and five killed in Baghdad, officials said.

In Mosul, a U.S. military spokesman said Wednesday U.S. troops killed a suspected terrorist and accidentally shot and killed a bystander during a skirmish with militants, CNN reported. Five others were arrested in the incident, which began when insurgents shot at troops who returned fire, a military spokesman said in a news release.

U.S. military officials said an unmanned drone shot a Hellfire missile at five insurgents who were firing rocket-propelled grenades at Iraqi soldiers, the spokesman said.

The drone was fired into a Basra neighborhood known to support the Mehdi Army of rebel Shiite cleric Moqtada Sadr.

At least 22 others were wounded in the violence that killed the five people in Baghdad, an Iraqi Interior Ministry official told CNN.